Subcellular Localization of β-Arrestins Is Determined by Their Intact N Domain and the Nuclear Export Signal at the C Terminus*
Subcellular Localization of β-Arrestins Is Determined by Their Intact N Domain and the Nuclear Export Signal at the C Terminus*
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DOI：
10.1074/jbc.m208109200
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发表时间：
2003-03
期刊：
影响因子：
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通讯作者：
Ping Wang;Yalan Wu;X. Ge;Lan Ma;G. Pei
中科院分区：
文献类型：
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作者：
Ping Wang;Yalan Wu;X. Ge;Lan Ma;G. Pei
β-Arrest in1和β-arrestin2在G蛋白偶联受体介导的信号转导中起关键作用，而β-arrestin1和β-arrestin2的亚细胞分布有很大不同。在本研究中，我们发现虽然β-arrestin1和β-arrestin2都能与泛素蛋白异肽连接酶(E3)MDM2相互作用，但只有β-arrestin2的表达导致MDM2从细胞核到细胞质的重新定位。进一步的研究表明，β-arrestin2而不是β-arrestin1以一种对软霉素B敏感的方式在细胞质和细胞核之间穿梭。在β-arrestin2的C末端的一个富含氨基酸的疏水区域(VXXXFXXLXL)被进一步证明是一个核输出信号，负责β-arrestin2的核外定位。在β-arrestin1的相应区域有一个单一的氨基酸差异(β-arrestin2中的Glu而不是Leu)，并且Glu到Leu的突变使β-arrestin1的亚细胞分布与β-arrestin2相似。此外，一系列缺失突变的数据表明，N结构域(残基1-185)对于两个β-arrestins的核定位是必不可少的，N结构域Val到Asp点突变的结果也支持这一观点。此外，我们的数据表明，通过蛋白质/蛋白质相互作用，β-arrestin2的核质穿梭是MDM2和JNK3细胞质重新定位所必需的，JNK3是另一种众所周知的β-arrestin2结合蛋白。因此，我们的研究表明，核输出信号基序和β-arrestins的N结构域都是调节其亚细胞定位的关键，β-arrestin2可能通过改变其结合伙伴如MDM2和JNK3的亚细胞分布来调节其功能。
β-Arrestin1 and β-arrestin2 play a key role in the regulation of G protein-coupled receptor-mediated signaling, whereas the subcellular distribution of β-arrestin1 and β-arrestin2 has been shown to be quite different. In this study, we found that although both β-arrestin1 and β-arrestin2 are able to interact with ubiquitin-protein isopeptide ligase (E3) Mdm2, only expression of β-arrestin2 leads to the relocalization of Mdm2 from the nucleus to the cytoplasm. Further study reveals that β-arrestin2 but not β-arrestin1 shuttles between the cytoplasm and nucleus in a leptomycin B-sensitive manner. A hydrophobic amino acid-rich region (VXXXFXXLXL) at the C terminus of β-arrestin2 was further demonstrated to serve as a nuclear export signal responsible for the extranuclear localization of β-arrestin2. In the corresponding region of β-arrestin1, there is a single amino acid difference (Glu instead of Leu in β-arrestin2), and mutation of Glu to Leu conferred to β-arrestin1 similar subcellular distribution to that of β-arrestin2. Moreover, data from a series of deletion mutations demonstrated that the N domain (residues 1–185) was indispensable for the nuclear localization of both β-arrestins, and the results from a Val to Asp point mutation in the N domain also supported this notion. In addition, our data showed that nucleocytoplasmic shuttling of β-arrestin2 was required, via protein/protein interaction, for the cytoplasmic relocalization of Mdm2 and JNK3, another well known β-arrestin2-binding protein. Our study thus suggests that both the nuclear export signal motif and the N domain of β-arrestins are critical for the regulation of their subcellular localization and that β-arrestin2 may modulate the function of its binding partners such as Mdm2 and JNK3 by alteration of their subcellular distribution.